To the Editor: In a study comparing 4 popular weight-loss diets, Dr Gardner and colleagues1 concluded that the Atkins diet (very low in carbohydrates) yielded greater weight loss than the Ornish diet (very high in carbohydrates).1 Differences in carbohydrate quality between these diets and intervention fidelity suggest a different conclusion. We believe that the study is not a fair test of these diets because poor adherence to the Atkins and Ornish diet stipulations at the outset were evident.